Referring to FIG. 1, a schematic representation is depicted of a commercially available direct laser metal sintering machine 100. Those skilled in the art are familiar with direct laser metal sintering and the general process of using a laser beam to melt a solid, powdered metal to ultimately form continuous metal layer slices that are fused together sequentially to form a three dimensional object. Consequently, only a low level description of the components of a direct laser metal sintering machine and the process carried out by these contemporary components is provided in furtherance of brevity.
This direct laser metal sintering machine 100 includes a chamber delineated by walls (not shown) within which the selective sintering process takes place. As used herein, sintering refers to melting of solid particles in furtherance of approaching or reaching near full density upon solidification of the melted particles. This chamber includes a working area 102 and a reservoir area 104 that are partially separated by a divider wall 106. On one side of the divider wall 106 in the working area 102 is a build piston 110 that vertically repositions a build platform 112, upon which resides a metal powder bed 116 and a sintered part 118. On the other side of the divider wall 106 in the reservoir area 104 is a metal powder dispenser piston 120 that vertically repositions a metal powder dispenser platform 122, upon which resides a reservoir of metal powder 126 that provides replenishing metal powder to the working area 102 during the sintering process.
In order to carry out the sintering process, the machine 100 includes a laser 130 that generates a laser beam 134. This laser beam is directed through a set of optics/lenses 132 prior to reaching a galvanometer 136. The galvanometer includes a controller and motor connected to one or more mirrors operative to reposition the laser beam 134 across the metal powder bed 116 to change the two dimensional position of the laser beam with respect to the metal powder bed.
In summary fashion, a master controller (not shown) of the machine 100 is responsible to control of the overall sintering process. In particular, the master controller controls the operation of the laser 130 to selectively power it on or off in order to provide or discontinue the laser beam 134. Moreover, the master controller is communicatively coupled to the galvanometer 136 in order to change the two dimensional position of the laser beam 134 upon the metal powder bed 116 and form a sintered metal layer 140 (e.g., one of the sintered metal layer slices of the eventual fabricated device). In exemplary form, the laser beam 134 may be scanned across the metal powder bed 116 in straight line in an X-direction, followed by an incremental shift in the Y-direction, followed by another scan across the metal powder bed in a straight line in the X-direction, with this process repeating until the laser beam has been moved across the working dimensions of the powder bed 116. Those skilled in the art are familiar with the controls necessary to scan a laser beam in two dimensions to form a sintered metal layer 140, accordingly, a more detailed recitation of this process has been omitted in furtherance of brevity.
After concluding the scanning of the laser beam 134, the sintered metal layer 140 is moved vertically downward by repositioning the build piston 110, which in turn vertically repositions the build platform 112 downward upon which the sintered metal layer sits. Also, the metal powder bed 116 is reset using a coater arm 144 that is operative to spread evenly a layer of powdered metal from the reservoir 126 across the cross-sectional area of the build platform 112 (including the metal layer 140) prior to carrying out the next laser scanning operation. Thereafter, the laser beam 134 is scanned across at least a portion of the cross-sectional area of the build platform 112 to form a subsequent sintered metal layer this is fused to the preceding sintered metal layer. This sequence of events (i.e., laser scanning and powdered metal layer reset) is repeated until the last sintered metal layer is formed, thereby signifying completion of the three dimensional object.
As depicted in FIG. 1, pre-existing additive manufacturing machines were limited by utilizing a single laser beam to sinter a powdered material. In cases where multiple products were manufactured within a single powder bed, this single laser needed to be repositioned by the galvanometer redundantly across the powder bed, which unnecessarily required additional time and resources. Conversely, it is more common to operate two or more additive manufacturing machines in parallel to each create a single duplicate device. But this requires rather large outlays of additional capital to purchase and maintain redundant additive manufacturing machines, to purchase and maintain duplicative powder reservoirs, and to tie up a single machine to only make a single device. Accordingly, there is a need to increase the efficiency of additive manufacturing machines to create multiple devices concurrently, without requiring the laser to scan across more of the powder bed than is necessary to sequentially fabricate the layers of a single device.